Along with the increase in the amount and speed of processing, heating parts having a larger power dissipation, such as a CPU, are installed in the recent electronic equipment, such as a personal computer, and the amount of heat generated by the heating parts is more and more increasing. In these electronic equipment, the variety of electronic parts used therein generally have an operating temperature limit due to the temperature dependency of the heat-resistance reliability and operating characteristic. Thus, it is an urgent subject to establish the technique for efficient radiation of the heat generated within the electronic equipment toward the outside thereof.
In general, the electronic equipment, such as a personal computer, includes a metal heat sink or so-called heat pipe etc. attached to the CPU etc. as a heat absorbing part, which diffuses the heat across the entirety of the electronic equipment by heat conduction, or an electromagnetic cooling fan attached onto the housing for radiating the heat from inside to outside of the electronic equipment.
For example, an electronic equipment, such as a notebook personal computer, on which electronic parts are densely mounted, has a small heat radiation space within the electronic equipment, and is capable of cooling a CPU having a power consumption of up to 300 watts by using a conventional cooling fan alone or a combination of the cooling fan and heat pipe. It is difficult, however, to sufficiently radiate the internal heat from a CPU having a power consumption above that value.
Even if the heat radiation is possible, it is essential to install a large blowing-capacity cooling fan, and if an electromagnetic cooling fan is used therefor in particular, silence is lost due to the noise such as a hissing sound by the rotary blades. In a personal computer used as a server, request for a smaller size and the silence is increasing along with the spreading use thereof, and accordingly, there occurs a problem in the heat radiation therefrom similarly to the notebook personal computer.
For efficient radiation of the increased amount of heat, use of a liquid-type cooling device which circulates refrigerant therethrough is studied. For example, JP-A-2003-67087 describes a liquid-type cooling device, wherein a personal computer body is provided with a heat-receiving head which receives heat from the heating parts of the personal computer body. A housing is also disposed which is provided with a connecting head, to which the heat from the heating parts is transferred through the heat-receiving head, a tube connected to the connecting head and filled with refrigerant, and a pump for circulating the refrigerant, which are disposed on the bottom of the personal computer body.